Definition
Magnetism is the physical force of attraction or repulsion between magnetic poles, produced by the alignment and motion of electric charges.
Why It Matters
It governs compasses, data storage, and planetary magnetic shields.
Core Concepts
- Magnetic Fields: Produced by electron spin and revolution. Field lines spread from North to South.
- Magnetic Domains: Clusters of aligned atoms. In permanent magnets, domains are aligned.
- Electromagnets: Coils of wire that become magnets when current flows through them.
- Magnetic Force on Moving Charges: A magnetic field exerts a force perpendicular to the charge’s velocity. This is how we steer electrons in old TVs or particles in accelerators.
- Lenz’s Law: The induced current creates a magnetic field that opposes the change that created it (Conservation of Energy).